1. Technical Field
The present invention relates generally to devices for fine tuning stringed musical instruments, and more particularly to an improved adjustable bridge system which secures the strings of the instrument on the instrument body while also providing for length, height, and spacing adjustments of the strings. The bridge system can be readily modified to provide only for length and height adjustments of the strings while retaining many of the overall advantages the invention.
2. Background Art
Stringed musical instruments are generally tuned in two ways: firstly, through harmonic tuning, which relates to string length and which is adjusted by altering the distance between the points at which a string contacts and rests upon the bridge and nut members of the instrument; secondly, through pitch tuning (also referred to as fine tuning), which relates to string tension and which is adjusted principally by tuning keys and secondarily by an adjustable bridge. As string tension is increased, the pitch raised, and as string tension is decreased, the pitch is lowered. Generally, the adjustable saddle provides for finer tuning than that achieved through tuning keys.
An adjustable bridge for a stringed instrument can provide a variety of mechanisms used to reposition its multiple saddles. In order to intonate each string harmonically by adjusting its length, the saddle of the string can be repositioned in the longitudinal direction (L). Usually, the saddle of each string can also be repositioned in the up/down, or height, direction (H) to adjust the string height. This serves to optimize and tailor the feel of the action of the instrument to the preferences of the musician. The option to reposition the saddle of each string in the latitudinal direction (S) to adjust the string spacing is a less common feature than the other two options, yet this adjustment can be just as essential if, for example, the user regularly pulls or pushes the outer strings off the playing surface of the neck when the outer strings are close to the edges of the neck.
Thus a bridge which provides length, height and spacing adjustment for each string is highly desirable. A bridge with all three adjustment option in combination will be referred to herein as LHS bridge. The prior art includes a variety of LHS bridges, some of which are considered below.
A bridge for a stringed instrument serves to transfer the vibrations of the strings to the instrument body, and the saddles are the points where most of this energy is transferred. Preferably, the vibrating energy of the string is never dampened by rattles or movements of the saddle, which is required to be rigid. Additionally, a maximum of energy is transferred from the point of string vibration at the saddle and into the instrument body. Satisfying these requirements has remained an enduring problem in the design of LHS bridges and of adjustable bridges in general, where each of the multiple saddles is traditionally required to be interconnected to the base of the bridge by multiple mechanical elements which are free to move in order to provide some or all of the separate adjustments. Thus each saddle is typically attached to the bridge by a connecting element which allows lateral free play but which weakens the rigidity of the saddle. Moreover, to provide height adjustment of the string, the saddle is typically required to be elevated in relation to its base or to the body of the instrument, such that a restricted amount of direct contact exists between the saddle and the instrument body. Therefore the flow of energy between the vibrating string and the instrument is likewise restricted.
Saddles adapted for use on acoustic stringed instruments, such as a steel-string guitar or a classical guitar, transfer the energy of the vibrating string directly downward into the instrument's soundboard. Therefore, the saddle is preferably perpendicular to the longitudinal line dividing the top face of the instrument. If the saddle angles away from the perpendicular, it will transfer the energy obliquely into the soundboard and will weaken the resonance of the instrument. Other stringed instruments such as solid body guitars likewise resonate optimally when the energy is transferred directly downward into the instrument. Thus the multiple saddles of an adjustable bridge preferably have a support which is perpendicular to the top face of the instrument and which is located below the point at which the string vibrates at the saddle. Since each of the saddles requires height adjustment, the mechanical elements employed for such a purpose should also serve as the perpendicular support. Traditionally, this has been partly resolved by using one or two height-adjusting screws that support and engage the saddles. The screws are typically located immediately next to the point at which the strings vibrate at the saddle, but they are not located underneath the string, which would provide advantages. Additionally, there is a very limited amount of space between the edge of the saddle and the point at which the string vibrates over the saddle. Therefore these screws have a diameter which is a small fraction of the width of the saddle and they provide a restricted amount of volume and of mass through which the vibrating energy of the string can be transferred downwardly.
Moreover, the ideal saddle should serve as an acoustically neutral connection between the string and the instrument in order to bring forth the natural sound of the instrument. It is widely recognized that the material used to make a saddle plays a significant role in the overall sound of a stringed instrument. Therefore the saddle material should not have an adverse characteristic impact on the resonating frequencies of the instrument. Accordingly, most of the builders of acoustic instruments, such as steel-string or classical guitars, long ago found it crucial that to select materials such as bone, different ivories, and other similar materials in order to produce a generally neutral saddle.
Known prior art adjustable bridges typically provide multiple saddles that must be repositioned relative to the supporting base of the bridge. In the prior art devices, each saddle is interconnected to the supporting base by mechanical elements such as screws which reposition the saddle. Alternatively, the saddle is adjusted by mechanical elements which apply an amount of pressure on the saddle significantly greater than the pressure applied by the string. This restricts the choice of material from which the saddles of an adjustable bridge can be fabricated; the preferred materials cannot be used because they tend to shatter under the pressure. In order not to shatter and in order to function properly, these saddles are typically made from various metals or artificial materials.
Saddles that include an array of mechanical elements are also prone to a loss of precision and integrity, either from wear and tear or from a typical succession of small accidental blows. This further diminishes the quality of the sound of the instrument and compels more visits to an instrument repairman.
Although the multiple saddles of prior art adjustable bridges can all be removed from the bridge, none are known that provide for easy frequent removal. Traditionally, a saddle is removed because it is damaged or functions improperly. In such a case, the saddle is replaced by an identical saddle that is painstakingly adjusted to the position previously occupied by the old saddle. This usually requires the use of one or more tools and may require the expertise of a repairman.
Finally, it should be noted that prior art adjustable bridges are typically provided as a single unit and are designed to be installed on one type of instrument only. Thus, for example, if such a bridge is adapted for use on a six-string instrument, it will not accommodate an additional saddle so that it can be used on a seven-string instrument without significantly altering the support base of the bridge and/or the device which attaches or anchors the bridge to the instrument. Likewise, this bridge cannot be used on a six-string instrument that uses different scale lengths for each string and thus may require a significantly slanted bridge.
Known prior art devices include those described, taught, or otherwise disclosed in the following patents:
U.S. Pat. No. 4,453,443, to Smith, which teaches a pitch stabilized string suspension system for minimizing detuning while playing by designing the string length between the string break point and the string attachment point as a function of the coefficient of friction and the deflection angle at the break point. The patent purportedly discloses novel designs of the components of the string suspension system, including the bridge, the saddle, the nut, and the tuning machine. The various embodiments of the invention provide adjustment in one or two dimensions while compromising or eliminating adjustments in the third. For instance, an embodiment providing for length and height adjustment provides no means for spacing adjustment. Additionally, the structural requirements of the saddles require the use of metals or artificial materials. Furthermore, the saddles cannot be replaceable easily and the height adjustment screws provide a restricted connection for the transfer of the energy of the vibrating string.
U.S. Pat. No. 4,497,236, to Rose, shows a fine tuning apparatus which functions as the bridge of a stringed instrument. It includes a base and a series of fine tuning elements, one for each string. Each fine tuning element includes a forward block and a saddle which is rotatable relative to the forward block. A string makes contact at a point on the saddle element and maintains surface contact with the saddle as the surface slopes downwardly and rearwardly from the contact point to a point where the string is clamped against the surface of an ear portion of the saddle. The rotatable position of the saddle can be adjusted relative to the forward block element, which results in a change in the tension of the string. However, the saddle cannot be adjusted for string spacing or string height, it cannot be easily replaced, and its structure requires that it be fabricated from metals or artificial materials.
U.S. Pat. No. 4,608,904, to Steinberger, discloses an anchoring and tuning mechanism that employs plug-ended strings slidably insertable into slots and cut-outs and tensioned by retraction of anchor members slidable in channels aligned with the strings. However, it does not provide means for harmonic tuning, or adjustment of the saddle in the longitudinal direction.
U.S. Pat. No. 4,649,788, to Matsui, teaches a bridge and means for mounting the rear end of each of a plurality of strings on the bridge. The bridge includes a plurality of saddles to which strings are individually attached. Each saddle is adjustable longitudinally for harmonic tuning and the saddle is adjustable for pitch without varying the effective length of the string. However, as with the patent to Rose, the saddle cannot be adjusted for string spacing, it is not easily replaceable, and its structure requires that it be fabricated from metals or artificial materials. This bridge also requires the use of a considerable number of mechanical elements which could weaken the rigidity of the saddle or rattle.
U.S. Pat. No. 4,672,877, to Hoshino et al., discloses a tailpiece and bridge assembly, comprising a pivotable housing attachable to the body of the instrument at the tailpiece. The pivoting movement of the housing provides for slight height adjustments in the strings, but it does not provide for longitudinal or lateral adjustments of the strings.
Finally, U.S. Pat. No. 5,520,082, to Armstrong et al., teaches a tremolo device for adjusting the string tension, which includes a base plate attached to the body of the instrument and a movable plate having first and second edges extending in a direction perpendicular to the strings. The movable plate is mounted to the base plate along the second edge of the movable plate about a pivot axis and in a horizontal position with its longitudinal axis perpendicular to the strings. The first edge of the movable plate is adapted to securely anchor the second end of each of the strings. The tuning devices are manually operable to stretch the associated strings between itself and the movable plate to apply a preselected tension force to each of the strings which bias the movable plate in a first direction of rotation about the pivot axis. The saddles can be adjusted for string length and string height only. Furthermore, the method of adjusting the string lengths is difficult and imprecise, requiring that manual force be applied to the string before the saddle is tightened into position.
Other known devices include two adjustable bridge designs manufactured by Schaller Electronic, An der Heide 15, D-92353 Postbauer-Heng, Germany, one denominated the STM system, and the other denominated the 3-D6. Each system is well known in the industry. These bridges have individual saddles, each with a lateral threaded rod inserted into it. The rod receives a small threaded cylinder, known as a roller, which has a central groove that catches the string. When the roller is turned, it moves laterally and string spacing adjustments can be made. A shortcoming of the design is that the string is held by a moving part (namely, the roller) which cannot be completely rigid. Additionally, the design has a poor saddle-to-bridge contact. The flow of energy must go through the small roller, through the threaded lateral rod and then down into the body, which is a very indirect path. Furthermore, the roller and the rod are required to be made out of metal.
The foregoing patents reflect the current state of the art of which the present inventor is aware. Reference to, and discussion of, these patents is intended to aid in discharging Applicant's acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated patents disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein.